As mentioned by Rivera, et al. [1], intravenous (IV) therapy springs from the need to transfer blood from one human being to another, and dates from around 1492. Currently, catheter-insertion devices are common; when a catheter is inserted in a patient in order to administer a liquid intravenously, a disposable needle is used that passes through a catheter to puncture a vein and enable the probe to enter. Subsequently, the needle is withdrawn, leaving the catheter in place so that it can be connected to an intravenous bag or bottle, or to a tip for later use.
There is epidemiological evidence, worldwide, that the main unease regarding mishaps in the use of perforating instruments and their later disposal as a part of infectious hospital waste relates to possible transmission of the AIDS virus and, more often, of the hepatitis-B and hepatitis-C viruses, due to lesions caused by needles that are contaminated with human blood. Hence, new products have been designed incorporating special coverings for the needle, or mechanisms for withdrawing the latter into a protective chamber. Such devices are, for example, described in U.S. Pat. Nos. 4,747,831, 4,828,548, 5,129,884, 5,501,675, 5,817,058, 5,989,220, 7,771,394 and 7,740,615. Many of the devices described in the aforesaid patents consist of numerous parts that substantially drive up their manufacturing costs, as well as hampering the user's ability to feel whether the needle is correctly inserted into the patient. Other devices need to be operated with two hands, or their needles are liable to become prematurely withdrawn during transportation, storage or handling.
Furthermore, studies [2] show that the pain associated with the penetration of the skin by the needle is caused by friction and the thrust load that occurs when the needle is inserted. Davis [3] states that there is only one relevant factor that affects the forces that occur when the skin is penetrated—i.e. the ratio between the force of the insertion and the surface area of the point. It should be added that pain—which is a mechanism for protecting the organism and occurs whenever tissue is being damaged, making the individual react in order to eliminate the painful stimulus—has been divided into two types—fast and slow. The former type is produced within around 0.1 seconds of receiving the stimulus, also being described as penetrating, stabbing, sharp, acute, electric, etc. For example, such pain is felt when a needle is stuck into the skin or when the latter is cut with a knife, though no quick, pulsing pain is felt in most of the deeper body tissues.
Since we know that venous canalization is currently carried out manually in patients, the staff who perform this operation must be very experienced and employ a special, highly polished technique in order to avoid hurting and harming the patient when they insert the needle into the vein. However, despite such experience and skill, the patient can sometimes be subjected to pain and multiple skin punctures when an appropriate vein cannot be found or due to bad insertion techniques. Some attempts have been made to produce devices aimed at reducing or doing away with pain by improving injection techniques or eliminating the need for such specialized techniques—e.g. the Auxiliary Device for Painless Venous Perforation (Spanish initials: DAPV), patented in Cuba in 1966, and the Device for Procuring Painless Peripheral Venous Catheterization (Mexican patent number: 247215).
The first of these devices, the DAPV, is a type of “crossbow” in which a plastic syringe is mounted along with its plunger and needle, which is shot into the selected vein by means of a mechanism that is triggered one single time by the technician carrying out the process.
The second of them, the Device for Procuring Painless Peripheral Venous Catheterization, consists of a mounting framework for the mechanisms for supporting, attaching and triggering catheters or hypodermic needles, with both patents permitting the uncontrolled shooting of the said catheters or hypodermic needles.
As can be inferred from this text, an intravenous catheter device must have certain qualities, including the ability to: (a) reduce or eliminate pain; (b) reduce the chances of multiple skin punctures; (c) reduce the need for special injection skills and experience, in addition to which it must: (d) be fitted with a safety system and (e) be easy to use, and these are the features that this invention claims to have.